To make butter easier to cream with sugar or flour, take the amount of butter required directly from the refrigerator and pop it into the microwave on Medium-Low (30%) power for a few seconds. (it will take about 30 seconds to soften 125 mL (1/2 cup) of butter on the defrost or Medium setting in a 700 watt oven). To soften a 454 gram (1 pound) block, cut it into quarters before microwaving.
Remember these tips to Keeping Butter Fresh